No description available.

Thesis (Ph.D.)--University of Western Australia, 2006.

No description available.

Research suggests hypertension is associated with reduced somatosensory perception. Further, natural fluctuations in blood pressure (BP) across the cardiac cycle have been shown to modulate nociceptive responding, pain and tactile sensitivity, suggesting that arterial baroreceptors may be important moderators of somatosensation. This thesis further examined the influence of natural fluctuations in BP, and thus baroreceptor activity, across the cardiac cycle on electrocutaneous pain and tactile sensory thresholds and pain-related evoked potentials (PREPs) in normotensive individuals. Study 1 found pain thresholds were higher, i.e. pain was reduced, during systole compared to diastole. Further analysis revealed only participants with low-normal systolic BP displayed this cardiac cycle modulation, suggesting tonic BP may moderate cardiac cycle-related pain modulation. In the second study, tactile sensory thresholds did not vary across the cardiac cycle. However, when participants were split into high-normal and low-normal BP groups, interactions between BP and tactile sensory thresholds across the cardiac cycle were revealed. This finding suggests tonic BP may be an important factor determining the cardiac cycle modulation of tactile sensation. Study 3 found no variation in the N2 or P2 peak amplitudes, or N2-P2 peak-to-peak amplitudes across the cardiac cycle at scalp recording sites Cz, C3, or C4. Furthermore, BP median split analyses revealed no BP Group or interaction effect. As previous work reported a systolic dampening of PREPs, these data suggest the cardiac cycle-related modulation of PREPs may not be as robust as other measures of pain such as the nociceptive flexion reflex. Study 4 reported, in line with Study 3, no cardiac cycle related modulation of PREPs following stimulation of the right and left hands. However, a Hand x Scalp Electrode Site x Interval interaction was revealed for N2 peak amplitudes. These data suggest that the combination of side of stimulation and scalp recording site may be important in determining the patterning of PREPs across the cardiac cycle. Taken together, the findings of these studies suggest that pain perception, and to a lesser extent tactile sensation, are influenced by natural variations in BP across the cardiac cycle. However, modulation appears dependent on tonic BP. Conversely, pain-related brain activity across the cardiac cycle was not affected by tonic BP, but may be influenced by the combination of stimulation and recording sites.

Bibliography: leaves 306-353. / xiii, 353 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Utilizing a paired transcoronary sampling technique, serial determination of myocardial drug content was determined following intravenous bolus injection in patients undergoing diagnostic cardiac catheterization for the investigation of chest pain. There was significant modulation of haemodynamic effects of all three drugs according to changes in systolic interval. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, Queen Elizabeth Hospital, Cardiology Unit

published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Medical Sciences

No description available.

Previously, at Brunel University, two computer programs had been developed to facilitate the analysis of the diastolic material properties of the human left ventricle. These two computer programs consisted of; a finite element program, "XL1", which ran upon a Cray-1S/1000 and a post-processor and pre-processor, "HEART", which ran upon the Multics computer system. The computer program "HEART" produced the finite element model, which was then solved by "XL 1", and it also allowed for plotting the results in graphical form, The patient data was supplied by the Royal Brompton Hospital in the form of digitised cine-angiographic X-ray data plus pressure readings. The first stage was to transfer the two separate computer programs "HEART" and "XL 1" to the Sun Workstation system. The two programs were then combined to form a single package which can be used for the automated analysis of the patient data. An investigation into the effect that the elastic modulus ratio has upon the deformation of the left ventricle during diastole was performed. It was found that the effect is quite small and that using this parameter to match overall shape deformation would be extremely sensitive to the accuracy of the initial data. The main part of this work was the implementation of active cardiac contraction, by means of a thermal stress analogy, into the finite element program. This allows the systolic part of the cardiac cycle to be analysed. The analysis of the factors that affect cardiac contraction, including the material properties and boundary conditions was performed. This model was also used to investigate the effect that conditions such as ischaemia and the formation of scar tissue have upon the systolic left ventricle. The use of the thermal stressing analogy for cardiac contraction was demonstrated to mirror global and local deformation when applied to a realistic ventricular geometry.

[Truncated abstract] This thesis concerns itself primarily with the impact of exercise training on cardiac and vascular adaptations in humans. It contains longitudinal studies of individuals at either end of the physical activity spectrum; young elite athletes and obese children and adolescents. The study of these diverse groups was intentional, as a particular interest was to investigate the possible inter-relationships between morphological adaptations in the heart, evident in both obese and athletic populations, and the possible consequences of such adaptations for cardiac function. Whilst there exists a long tradition of echocardiographic assessment of cardiac dimensions and mass in both athletic and clinical populations, investigation of the impact of each of these “conditions” on cardiac diastolic function is novel, and has been facilitated by recent advances in the technical approach to diastolic function assessment in humans. Studies presented in the following chapters utilise advanced echocardiography imaging combined with pulse wave and tissue Doppler approaches to investigate the effects of exercise training regimen on wall thickness and ventricular mass, as well as diastolic function indices. State-of-the-art vascular imaging approaches have also been used in these populations to determine whether changes in vascular wall thickness, diameter or function occur with training in the elite athletes or obese youth.

Thesis (Ph.D.)--Biomedical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Oshinski, John N.; Committee Member: Fyfe, Derek A.; Committee Member: León, Angel R.; Committee Member: Skrinjar, Oskar; Committee Member: Taylor, W. Robert.